Last line indicator



22,1957 YUAN SHUEN WANG 2,778,473

LAST LINE INDICATOR Filed Sept. 21, 1954 22 mm w 20 l8 l7 fl wflq/ sM l-gi \iw /9 I W M 24- 25 E 0 5/ 46 23 v INVENTOR. YVA/V aqua/v WANG LAST LINE INDICATOR Yuan Shuen Wang, Hong Kong, China Application September 21, 1954, Serial No. 457,442

4 Claims. (Cl. 197189) This invention relates to improvements in last line indicators for typewriters.

The primary object of the invention is to provide a more practical and efiicient device of this character which is adapted to be incorporated in the manufacture of typewriters and to be installed as an attachment to typewriters.

Another important object of the invention is the provision of a device of the character indicated above which is simpler in construction, composed of a minimum of simple and rugged parts, is mechanically superior, is more reliable and dependable in action, and can be installed, adjusted and operated more easily.

A further important object of the invention is to provide a device of the character indicated above which can be made, either as original equipment or as an attachment, in serviceable and attractive forms at relatively low cost.

Other important objects and advantageous features of the invention will be apparent from the following description and the accompanying drawings, wherein, for purposes of illustration only, a specific embodiment of the invention is set forth in detail.

Figure 1 is a fragmentary front elevation, showing said embodiment adjusted for regular length typewriter paper;

Figure 2 is a fragmentary transverse vertical section taken on the line 22 of Figure 1;

Figure 3 is an enlarged fragmentary transverse vertical section taken on the line 33 of Figure 1, showing the hammer arm or lever in operative position in full lines and in retracted inoperative position in phantom lines;

Figure 4 is a view similar to Figure 3 showing another position of the trip lever; and

Figure 5 is an enlarged fragmentary vertical longitudinal section taken on the line 55 of Figure 2.

Referring in detail to the drawings, wherein like numerals designate like parts throughout the several views, the numeral 7 generally designates a typewriter carriage having a platen 8 including a ratchet wheel 9, and a shaft 10 having a knob 11 thereon, the shaft 10 being journaled through a carriage frame arm 12.

In accordance with the present invention a driving sprocket wheel 14 is circumposed upon and fixed to the shaft 10 in axially spaced relation to the frame arm 12 and the knob 11, and an idler sprocket wheel 15, preferably of the same diameter as the drive sprocket wheel 14 is journaled on a stub shaft 16 projecting laterally from and fixed, in suitable manner, to the frame arm 12 at a point spaced rearwardly from the drive sprocket Wheel 14, and preferably in horizontal and vertical alignment with the wheel 14.

A sprocket chain 17 is trained around and between the sprocket wheels 14 and and is composed of pairs of links 18 connected by pivots 19. One of the pivots 19 has an extension 20 extending in an inboard direction toward the frame arm 12, the extension 20 being a trip finger or pin.

Fixed to the frame arm 12, as indicated at 21, .preferably in axial alignment with the idler sprocket wheel 15, is a circular concave convex bell 22 which is larger in diameter than the sprocket wheel 15 and has a peripheral edge 23 located about midway between the sprocket Wheels 14 and 15.

nited States Patent 0 "ice Fixed to the frame arm 12 and projecting in an outboard direction therefrom at a point rearwardly of and above the axis of the platen shaft 10 is a stub shaft 24 having an axially outward end 25 located close to and spaced from the inboard side of the drive sprocket wheel 14.

Journaled on the stub shaft 24 at its outboard end and retained by a head 26 on the outboard end 25 of the stub shaft 24 is a trip lever 27. The trip lever 27 comprises a flat, generally triangular body 28 having right angular'ly related intersecting edges 29 and 30 and a hypotenuse edge. The hypotenuse edge 31 is indented to provide a circumferential notch 32 having a convex curved portion 33 concentric with the stub shaft 24 on which the trip lever is pivoted, and radial stop shoulders 34 and 35, at opposite ends of the notch. The stub shaft 24 traverses the trip lever body 28 at a point close to the notch 32 and mid-way between the ends of the notch 23 and spaced across the body 23 from the intersection 36 of the edges 29 and 30.

A trip arm 37 projects from the intersection 36 at a slight forward angle with respect to a line bisecting the intersection, and the trip arm 37 is long enough to extend into the path of the trip pin 20 on the sprocket chain 17 in the normal unoperated position of the trip lever 27, shown in full lines in Figure 2 and in phantom lines in Figure 3.

Iournaled on the stub shaft 24 at a point spaced from the frame arm 12 and from the trip lever 27 is a bell hammer lever 38. The bell hammer lever 38 comprises a fiat generally rectangular body 39, traversed approximately centrally by the stub shaft 24. From the lower rearward corner 40 of the body 39 projects a hammer arm 41 terminating at its free lower end in a hammer head 42. From the upper rear corner 43 of the body 39 projects a short diagonal lug 44. The lug 44 is only long enough to engage a fixed pin 45 projecting in an outboard direction from the frame arm 12 at a point spaced above and slightly to the rear of the stub shaft 24.

Another lug 46 projects from the outboard side of the body 39 of the bell hammer lever 38 at a point near the lower edge 47 of the body 39 and spaced forwardly from the hammer arm 41, the lug 46 being positioned to be engaged at different times with the stop shoulders 34 and 35 of the notch 32 of the trip lever body 28.

A helical spring v48 is circumposed on the stub shaft 24 at the inboard side of the bell hammer lever 38. The inboard end of the spring 48 is secured to the stub shaft 24, as indicated at 49 and the outboard end of the spring 48 is secured to the trip lever 38 as indicated at 54). The spring 48 serves to yieldably urge the bell hammer lever 38 in a direction to apply the hammer head 42 against the periphery 23 of the bell22.

A helical spacing and positioning spring 51 is circumposed on the stub shaft 24 and is compressed between the bell hammer lever 38 and the trip lever and is secured at its opposite ends to the bell hammer lever 38 and the trip lever 27, so as to yieldably resist rotation of the bell hammer lever 38 and the trip lever 27 relative to each other.

The diameters of the sprocket wheels 14 and 15 and the length of the sprocket chain 17 are determined by the diameter of the platen 8 and by the length of the typewriter paper to be used in the associated typewriter. Secured at 52 on a forward part of the carriage frame arm 12 is a pointer 53 having a free end 56 located close to the periphery 55 of the platen knob, and the periphery 55 is provided at a predetermined interval and at predetermined points with a legend 56, such as the letter R, and a legend 51.,such as the letter F, indicating settings of the knob with respect to regular length typewriter paper-and legal size or foolscap paper, respectively.

ar /ears The locations of the legends 56 and 57 on the knob are chosen so that the hammer head 4-2 will strike the hell 2?. as the paper, through normal operation of the typewriter, is carried around the platen 8 to a predetermined point chosen for the last line to be typewritten on the paper.

in operation, as the upper flight of the sprocket chain 17 is moved rearwardly in the direction of the arrows as the end of the paper approaches, the trip pin 20 engages the trip lever trip arm 37, and, as shown in phantom lines in Figure 3 of the drawings, the hammer head 42 is drawn forwardly by engagement of the stop shoulder 3d with the log 46 on the bell hammer lever 38, against the resistance of the spring 48. As the upper flight of the chain 17 progresses further in a rearward direction, the trip arm 37 will become disengaged from the trip pin 20, thereby freeing the spring 48 to snap the hammer head 42 against the periphery 23 of the bell 22, thereby audibly indicating to the typist that the last line to be typewritten has been reached.

It will be understood from the foregoing that a typist is not required to watch any visual indicating means after setting the knob 11 following insertion of the paper in the machine, but can type freely until the bell 22 is heard.

What is claimed is:

1. in combination, a typewriter carriage having a frame including a frame arm, a platen having a platen shaft journaled through said frame arm, said platen shaft having a free end having a platen rotating knob thereon, a first sprocket wheel circumposed upon and fixed to rotate with said platen shaft, a second sprocket wheel rotatably mounted on said frame arm indaterally spaced relation to said first sprocket wheel, an endless sprocket chain trained around and extending between said sprocket wheels, a trip finger on and projecting laterally from said sprocket chain, and bell mechanism mounted on said frame arm, said bell mechanism comprising a hell, a bell hammer lever having a hammer arm normally disposed in contact with the bell, a trip lever associated with and held in operative engagement with the bell hammer lever at all times during normal operation of the machine and movable relative to and out of operative engagement with the bell hammer lever only when the sprocket chain is moved backwardly in response to rotation of the platen in a direction opposite to that in which it is rotated during normal operation of the machine, spring means associated with said frame arm and said bell hammer lever and urging the bell hammer lever toward effective engagement with the bell, and a trip arm on said trip lever arranged for operative engagement with the trip finger on the sprocket chain as the platen is rotated in one direction.

2. In combination, a typewriter carriage having a frame including a frame arm, a platen having a platen shaft journaled through said frame arm, said platen shaft having a free end having a platen rotating knob thereon, a first sprocket wheel circumposed upon and fixed to rotate with said platen shaft, a second sprocket wheel rotatably mounted on said frame arm in laterally spaced relation to said first sprocket wheel, an endless sprocket chain trained around and extending between said sprocket wheels, a trip finger on and projecting laterally from said sprocket chain, and bell mechanism mounted on said frame arm, said bell mechanism comprising a bell, a bell hammer lever having a hammer arm normally disposed in contact with the bell, a trip lever associated with and held in operative engagement with the bell hammer lever at all times during normal operation of the machine and movable relative to and out of operative engagement with the bell hammer lever only when the sprocket chain is moved backwardly in response to rotation of the platen in a direction opposite to that in which it is rotated during normal operation of the machine, spring means associated with said frame arm and said bell hammer lever and urging the bell hammer lever toward effective engagement with the bell, a trip arm on said trip lever arranged for operative engagement with the trip finger on the sprocket chain as the platen is rotated in one direction, and a stub shaft projecting from said frame arm on which said trip lever and said bell hammer lever are pivoted.

3. In combination, a typewriter carriage having a frame including a frame arm, a platen having a platen shaft journaled through said frame arm, said platen shaft having a free end having a platen rotating knob thereon, a first sprocket wheel circumposed upon and fixed to rotate with said platen shaft, a second sprocket wheel rotatably mounted on said frame arm in laterally spaced relation to said first sprocket wheel, an endless sprocket chain trained around and extending between said sprocket wheels, a trip finger on and projecting laterally from said sprocket chain, and bell mechanism mounted on said frame arm, said bell mechanism comprising a bell, a bell hammer lever having a hammer arm normally disposed in contact with the bell, a trip lever associated with and held in operative engagement with the bell hammer lever at all times during normal operation of the machine and movable relative to and out of operative engagement with the bell hammer lever only when the sprocket chain is moved backwardly in response to rotation of the platen in a direction opposite to that in which it is rotated during normal operation of the machine, spring means associated with said frame arm and said bell hammer lever and urging the bell hammer lever toward effective engagement with the bell, a trip arm on said trip lever arranged for operative engagement with the trip finger on the sprocket chain as the platen is rotated in one direction, a stub shaft projecting from said frame arm on which said trip lever and said bell hammer lever are pivoted, and lug and slot means on said trip lever and bell hammer lever providing for limited movement of the trip lever and bell hammer lever relative to each other.

4. In combination, a typewriter carriage having a frame including a frame arm, a platen having a platen shaft journaled through said frame arm, said platen shaft having a free end having a platen rotating knob thereon, first sprocket wheel circumposed upon and fixed to rotate with said platen shaft, a second sprocket wheel rotatably mounted on said frame arm in laterally spaced relation to said first sprocket wheel, an endless sprocket chain trained around and extending between said sprocket wheels, a trip finger on and projecting laterally from said sprocket chain, and bell mechanism mounted on said frame arm, said bell mechanism comprising a bell, a bell hammer lever having a hammer arm normally disposed in contact with the bell, a trip lever associated with and held in operative engagement with the bell hammer lever at all times during normal operation of the machine and movable relative to and out of operative engagement with the bell hammer lever only when the sprocket chain is moved backwardly in response to rotation of the platen in a direction opposite to that in which it is rotated during normal operation of the machine, spring means associated with said frame and said bell hammer lever and urging the bell hammer lever toward effective engagement with the bell, a trip arm on said trip lever arranged for operative engagement with the trip finger on the sprocket chain as the platen is rotated in one direction, said platen rotating knob having a periphery, circumferentially spaced legends on said periphery, and a pointer mounted on said frame arm and having a free end located close to said periphery.

References Cited in the tile of this patent UNITED STATES PATENTS 1,376,996 Beland May 3, 1921 1,685,314 Davis 0 Sept. 25, 1928 2,571,996 Alleman Oct. 23, 1951 FOREIGN PATENTS 400,604 Germany Aug. 15, 1924 

